Pyridylmethylsulfinylcarbamates

ABSTRACT

R-SO-CO-N(-R1)-R2 HERBICIDAL ACTIVE SULFOXIDE COMPOUNDS ARE DESCRIBED HEREIN. THE COMPOUNDS HAVE THE FOLLOWING GENERIC FORMULA:   WHEREIN R IS SELECTED FROM PYRIDYLALKYL, R1 AND R2 CAN BE THE SAME OR DIFFERENT AND CAN BE SELECTED FROM THE GROUP CONSISTING OF LOWER ALKYL, CYCLOALKYL, ALKENYL AND BENZYL.

United States Patent 3,816,435 PYRIDYLMETHYLSULFINYLCARBAMATES Francis Harry Walker, Mill Valley, Califi, assignor to Staulfer Chemical Company, Westport, Conn.

No Drawing. Filed Aug. 14, 1972, Ser. No. 280,382 Int. Cl. C07d 31/48 US. Cl. 260-2943 F 9 Claims ABSTRACT OF THE DISCLOSURE DESCRIPTION OF THE INVENTION This invention is directed to a novel group of compounds which may be generally described as sulfoxide derivatives of thiocarbamates which are highly active herbicides. The compounds of the present invention are represented by the generic formula:

wherein R can be selected from the group consisting of pyridylalkyl, R and R can be the same or different and can be selected from the group consisting of lower alkyl, cycloalkyl, alkenyl and benzyl.

The above-noted compounds can be prepared by reacting an oxidizing agent such as peracetic acid or m-chloroperoxybenzoic acid with a thiocarbamate compound corresponding to the following formula:

0 R1 R-s-i 7N wherein -R, R and R have 'been defined above. The reaction is carried out in the presence of a solvent such as chloroform, methylene chloride, benzene or toluene, and at a reduced temperature of from about -25 C. to about 15 C. The amount of oxidizing agent used must be at least one molar equivalent to form the sulfoxide deriva tive.

The thiocarbamate compounds are known herbicides and their method of synthesis is known; see US. Pats. 2,913,327, 2,983,747, 3,133,947, 3,175,897 and 3,l85,- 720 for example. However, the use of these thiocarbamates as reactive intermediates to form other compounds that also have pesticidal activity is unexpected.

In order to illustrate the merits of the present invention the following examples are provided:

EXAMPLE 1 A solution was formed containing 6.0 g. (0.024 mole) S- S-pyridylmethyl -N-ethyl-N-butoylthiocarbamate dissolved in 100 cc. of methylene chloride. This solution was cooled to l5 C. in a Dry Ice bath. Then, 4.5 g. (0.026 mole) of m-chloroperoxybenzoic acid was added portionwise over a period of 1.5 minutes. The mixture was stirred for 1 hour and the temperature was raised to 5 C. and held for 0.5 hours. Then, the mixture was warmed to room temperature. The reaction mixture was transferred to a separatory funnel and treated 4 times with m1. of a 5% sodium carbonate solution followed by 2-50 ml.

TABLE I O 0 R1 II II R- S-C-N Compound number R R1 R2 1 'C2H5 ll-CrHn -CHa- 2 -C2H| H'CQHQ -CH: N

3 -CHa-CH=CH: -CHa--CH=CH:

CH I

4. Same as above n-C H n-C,H

5 do C2Hs S 6..-. C:H; Same as above.

Hz N 7 Same as above 11-03111 n-CaH 8 CzH water washes. After drying over MgSO the solvent was removed 'by vacuum to yield 5.0 g. of product, n -1.5471.

Other compounds were prepared in an analogous manner starting with the appropriate starting materials as outlined above. Preceding Table I is a table of compounds representative of those embodied by the present invention. Compound numbers have been assigned to them and are used for identification throughout the balance of the specification.

Herbicidal Screening Tests As previously mentioned, the novel compounds herein described are phytotoxic compounds which are useful and valuable in controlling various plant species. Compounds of this invenion are tested as herbicides in the following manner.

A. Preemergence Herbicide Screening Test: Using an analytical balance, 20 mg. of the compound to be tested is weighed out on a piece of glassine weighing paper. The paper and compound are placed in a 30 ml. widemouth bottle and 3 ml. of acetone containing 1% Tween 20 is added to dissolve the compound. If the material is not soluble inacetone, another solvent such as water, alcohol or dimethylformamide (DMF) is used instead. When DMF is used, only 0.5 ml. or less is used to dissolve the compound and then another solvent is used to make the volume up to 3 ml. The 3 ml. of solution is sprayed uniformly on the soil contained in a small Styrofoam fiat one day after planting weed seeds in the flat of soil. A No. 152 De Vilbiss atomizer is used to apply the spray using compressed air at a pressure of 5 lb./sq. in. The rate of application is 8 lb./ acre and the spray volume is 143 gal/acre.

On the day preceding treatment, the Styrofoam flat which is 7 inches long, 5 inches wide and 2.75 inches deep is filled to a depth of 2 inches with loamy sand soil. Seeds of seven different weed species are planted in individual rows using one species per row across the width of the flat. The seeds are covered with soil so that they are planted at a depth of 0.5 inch. The seeds used are hairy crabgrass (Digitaria sanguinalis), yellow foxtail (Setaria glauca), watergrass (Echinochloa crusgalli), red oat (Avena sativa), redroot pigweed (Amaranthus retroflexus), Indian mustard (Brassl'ca juncea) and curly dock (Rumex crispus). Ample seeds are planted to give about 20 to 50 seedlings per row after emergence depending on the size of the plants.

After treatment, the flats are placed in the greenhouse at a temperature of 70 to 85 F. and watered by sprinkling. Two weeks after treatment the degree of injury or control is determined by comparison with untreated check plants of the same age. The injury rating from to 100% is recorded for each species as percent control with 0% representing no injury and 100% representing complete kill.

B. Postemergence Herbicide Screening Test: Seeds of six plant species, including hairy crabgrass, watergrass, red oat, mustard, curly dock and Pinto beans (Phaseolus vulgaris) are planted in the Styrofoam flats as described above for preemergence screening. The fiats are placed in the greenhouse at 70 to 85 F. and watered daily with a sprinkler. About 10 to 14 days after planting when the primary leaves of the bean plants are almost fully expanded and the first trifoliate leaves are just starting to form, the plants are sprayed. The spray is prepared by weighing out 20 mg. of the test compound, dissolving it in ml. of acetone containing 1% Tween 20 and then adding 5 ml. of water. The solution is sprayed on the foliage using a No. 152 De Vilbiss atomizer at an air pressure of 5 1b./sq. in. The spray concentration is 0.2% and the rate is 8 lb./acre. The spray volume is 476 gal./ acre.

Injury ratings are recorded 14 days after treatment. The rating system is the same as described above for the preemergence test.

The results of these tests are shown in Table II.

TABLE IL-HERBICIDAL ACTIVITY-SCREENING RESULTS Percent control at 8 lb./a. Compound number Preemergence Postemergence Average for seven species in the preemergence test and for six species in the postemergence test.

wherein R is selected from, pyridylmethyl, R is selected from the group consisting of lower alkyl, having 1 to 4 carbon atoms, allyl and benzyl, R is selected from the group consisting of lower alkyl having 1 to 4 carbon atoms, cyclohexyl and allyl.

2. The compound as set forth in claim 1 wherein R is N R1 is -'C3H5, R2 is Il-C4Hg.

3. The compound as set forth in claim 1 wherein R is R1 is C2H5, R2 is n-C H 4. The compound as set forth in claim 1 wherein R is R1 is and R2 is 5. The compound as set forth in claim 1 wherein R is N R1 is H'C3H7 and R2 is n-C H 6. The compound as set forth in claim 1 wherein R is 1 is c3H5 and R is 7. The compound as set forth in claim 1 wherein R is R1 is 'C2H5 and R2 is R; is

8. The compound as set forth in claim 1 wherein R is and R is C H 5 References Cited UNITED STATES PATENTS 3 579 525 5/1971 Tilles et a1 260-294.8 E R 1s H-C3H7 and R218 n-C3H7' 9. The compound as set forth in claim 1 wherein R is 10 3634436 1/1972 Domemco 260.4943 F ALAN L. ROTMAN, Primary Examiner f] US. Cl. X.R. 

